Delayed speech development in children is accounted for various conditions. During the past 3 years and 2 months from January of 1970 to February of 1973, 163 children with delayed speech development visited our department. By analysing etiological conditions and evaluating the present status of these cases, we hope to find any reliable data for diagnosis, treatment and counseling of the patients. In conditional view, the 163 cases are classified into the following 4 groups : 1) Mental defect : 42 cases, 2) Developmental expressive aphasia : 11 cases, 3) Cerebral palsy : 12 cases, 4) Hearing defect : 98 cases. In analysing the special features of each group and evaluating general features of all groups, the following parameters are adopted : 1) sex 2) age 3) family position 4) family status 5) general physical development 6) maternal history during pregnancy 7) past illness of the patients 8) receptive and expressive speech evaluation 9) types of hearing loss 10) degree of residual hearing in speech range.